1. Field of the Invention
The invention relates to dead end connectors for gripping and securing wires, such as the electrical conductors of power lines, and for maintaining them in tension. More specifically, the invention relates to a dead end of the type that employs wedge-shaped jaws to grip the conductors.
2. Description of the Related Art
Dead ends are couplings used to anchor electrical transmission lines to supporting structures such as towers or poles. The dead end typically connects the power line to an insulated mount attached to the supporting structure. Dead ends to which the invention relates must include a mechanism for gripping the conductor of the power line so that the tension on the line is delivered through the insulated mount to the supporting structure. Dead ends are characterized by robust construction from high strength materials to withstand the tension on power line, which may exceed several thousand pounds of force. Weather events, such as wind and ice may place an additional strain on the dead end.
A critical factor in the effectiveness of a dead end is the mechanism used to grip and hold the conductor of the power line. Many prior art dead ends use clamps compressed together by nuts and bolts. The clamping force developed by such mechanisms depends on the degree to which the clamp components are compressed together by the hardware. As will be apparent, the effectiveness of hardware-clamped dead ends is impaired by variation in the torque applied to the hardware by different installers. Under-tightening of the hardware reduces the retaining strength of the assembly, while over-tightening is known to cause stress related failure of dead end components.
U.S. Pat. Nos. 5,539,961 and 6,076,236 illustrate dead ends that improve over the hardware-clamped dead end by employing a pair of spring loaded wedge-shaped jaws to grip the conductor of a power line. The jaws travel in converging guides toward a gripping position in which they are wedged against the conductor. The dead ends include a latch for maintaining the jaws in an open position against the spring bias. Transverse teeth on the jaw inside faces bite into the conductor when the jaws are in the gripping position. Gripping force in the disclosed wedge dead ends is proportional to the tension on the power line. The steps of tightening bolts and the associated variability are eliminated. The wedge dead ends simplify installation and increase the consistency of the connection between the dead end and the power line.
While the above-described wedge dead ends have proven successful, further improvements in dead end design are possible. For example, the prior art wedge dead ends have many moving parts, which make them expensive to manufacture. The two movable, spring-loaded jaws of the prior art wedge dead ends are coupled for simultaneous movement. Because the jaws are coupled, any jarring or movement applied to one jaw is delivered to the other jaw and the latch mechanism. Frequently, the latch is prematurely triggered by attempts to arrange a stiff power line conductor between the jaws. The jaws must then be re-set to the open and latched position and the process repeated. Dead end installation is carried out on the tower or other support structure, making repetition of steps awkward, time consuming and dangerous.
There is a need in the art for a more cost effective and easy to use wedge dead end.